Grinding machine



Aug. 20; 1929. J BERG 1,725,126

GRINDING MACHINE Filed Aug. 16, 1927 4, ATTORNEYS Patented Aug. 20, 1929.

UNITED STATES ALFRED J. BERG, OF PORTSMOUTH, NEW HAMPSHIRE.

GRINDING MACHINE.

Application filed August 16, 192?.

My invention relates to grinding machines and particularly to machines adapted to reface' valve seats by grinding and truing same to predetermined limits.

It has for its general objects the provision of a power-driven grinding wheel and means for mounting same concentric with the axis of the cylinder or the like element upon which the valve is seated; and the provision of means whereby the application of the grinding wheel to the valve seat is manually controlled and the depth of metal to be removed is automatically limited by ready pre adjustment of a precision gauge.

With the foregoing and other and'more particular objects in view, as hereinafter pointed out, my invention consists of the features of improvement next herein set forth and described and illustrated in the accompanying drawings forming a partof this specification, and in which is shown that embodiment at present preferred by me as that best calculated to attain the features of advantage of my invention.

In these drawings,

Figure 1 is an elevational view, partly in section, of a grinding machine operatively associated with the valve seat of an engine cylinder;

Fig. 2 is a plan view thereof;

Fig. 3 is a plan view of an attachment for dressing the grinder Wheel; and

Fig. 4 is a sectional View of a modification.

Like reference numerals indicate like parts throughout the several figures, in which 1 is the fixture which supports the valve seat 3 and contains the guide 2 for the stem of the valve cooperating therewith. The valve is of course removed when the seat is ground. A motor 4 suitably connected to a power source has a shaft 5 on which is mounted the emery or like surfaced grinding wheel 6. The motor is mounted upon a base 7 to which it is clamped by the yoke 8 and bolts 9. A spindle 10 is screwed into the base 7, or otherwise rigidly afiixed thereto, and extends downwardly into the valve stem guide orbore 2, to Whose internal diameter it is adapted by the cylindrical bushing 11 screwed upon the spindle. The adapter bushing is free to turn in the bore.

A knurled micrometer thimble 13 consisting of a transversely split ring whose butting ends are drilled at 31 and threaded for a clamping screw 17 is threaded for engagement on the spindle 10. The thimble carries Serial No. 213,277.

thescale markings 14 which are adapted to register, as the thimble is revolved, with the scale markings 15 upon the flange 16 depending'from and integral with the motor base 7 By means of the clamping screw 17 passing 1 justment for the depth of cut desired, as will be later described. The grinder is preferably provided with a dressing attachment consisting of the support 18 held by the clamp 19 to the yoke 8 by screws and nuts 33. A head 20 on the support receives the threaded bolt 21 having the wing-nut 22, the bolt 21 retaining the thrust block 23 against the head 20. The frame members 24 extend from the head 20 and between these is the slide member 25 adapted to be reciprocated by the slide screw 26 carried by the thrust block 23 and engaging the member 25. The slide has the series of holes 27 adapted to receive, as required, the dressing tool 28 having the diamond point 29. The tool 28 is held by a set screw 30. As will be understood, the angle of the slide holder and dress ing tool is adjusted according to the conical. face of the grinding wheel, which in turn is determined by the desired bevel of the valve seat.

The method of 'utilizing my improved grinder is as follows:

I A cylindrical bushing adapted to the bore of the cylinder'in sliding contact is screwed upon the spindle. These are next inserted in the valve stem bore until the micrometer thimble rests upon the top of the wall 12 of the bore, the thimble being free to turn on its thread and adjusted to engage the wall of the bore before the grinder en ages the valve seat. The micrometer thim le is then rotated about the spindle in a direction to lower the motor base until the grinder wheel approaches the valve seat. The motor is then energized and further lowered until the grinder contacts with the valve seat, and a spark is struck by their friction. The micrometer gauge is then read and from the indicated point is calculated the desired setting, the difi'erence being the thickness of the metal to be removed. The motor is then stopped and the micrometer thimble rotated in the-reverse direction, while holding the motor stationary with the wheel in contact I by traversing the dressing tool across it by with the valve face, to a degree representing the thickness of the cut, as indicated by the micrometer reading, and there set by the tension-screw, whereby the thimble is held against further rotation upon the spindle.

The lower face 32 of the thimble will then motor being again energized and this cutting-is continued until the grinder removes no more metal. Whenever. the grinder has cut to the predetermi'ned depth, it-is automatically prevented from'cutting deeper by thecontact of the face 32 on the thimble with the stop face afforded by-the face 12. When -the cutting is. uniformly completed, the

grinder wheel may be run at high speed and swung about over the surface of the seat to give thefmetal a glass-like finish. When the seat is thus burnished, the motor is then stopped. During the cutting operation the face of the grinding wheel may be trued turning the screw, causing the slide toadvance andir'etract the diamond point In Fig. 4. I have disclosed a modification of the centering device whereby the grinder may be more readily adapted to grind valves of engines wherein the valve stem guides have been enlarged by wear or for some other reason are not of standard uniform size.'

In this modification the sleeve or bushing 11 is not threaded upon the spindle as shown in Fig. 1 with its exterior surface'of a size to rotate in the valve bore, but instead the spindle 10' of the grinder rotates in the bushing. and the bushing is fitted snugly in the valve stem guide. To this end the bushing 11 is provided with a knurled head or flange 35 at its upper end and immediately below the flange is tapered through a portion of its length, the difference in diameter at the upper and lower edges of the tapered portion being about one-eighth of an inch. At its lower end the diameter of the sleeve is further reduced by a tapered portion 37 terminating in a screw-threaded hub 38 and mounted on the tapered portion is a split ring 39 adapted to be expanded by means of a knurled nut 40 threaded on the hub 38. The grinder is provided with the micrometer thimble 13 threaded on the spin-- until the latter is expanded to iust fit the bore of the valve stem guide. The sleeve is then dropped in the valve stem guide and the tapered portion just below the knurled knob 35 at the upper end of the guide will wedge slightly in the guide, thereby centering the sleeve accurately in the valve stem guide and correspondingly centering the grinder with respect to the valve face. With this type of apparatus aset of bushings varying one-eighth of an inch in diameter will be provided, thus adapting the grinder to be fitted to valve stem guides of all sizes.

While I have shown and described a particular organization as my preferred embodiment of means best adapted for the grinding of large valve seats, I do not wish to be understood as intending to limit my invention thereto, since I consider such means merely as an exemplifying dlSClO- sure, and believe my lnvention to be capable of-practice in a diversity of forms within the scopeof the appended claims.

Iclaim:

1. A valve seat grinder comprising a base having a cylindrical stem extending downward therefrom adapted to fit the valve stem guide. an electric motor having its armature shaft provided at one end with a grinding wheel having a grinding face at the angle of the valve seat, means for clamping the electric motor to the base, and means for adjusting the height of the base relative to the valve seat comprising a ring having a screw threaded connection with the stem extending downward from the base and having its lower face adapted torest on the valve stem guide.

2. A valve seat grinder comprising a base provided with a cylindrical stem extending downward therefrom adapted to fit the valve stem guide, an electric motor havingits armature shaft provided at one end with a grinding wheel having a grinding face at the angle of the valve seat, means for clamp-' ing the electric motor to the base, and means for adjusting the height of the base comprising a ring adapted to rest on the valve stem guidehaving a screw thread connection with the stem carried by the base, and a scale marked on the periphery of the ring.

3. In a machine for grinding valve-seats, the combination of a motor, a cutting wheel driven thereby, a motor base, a support for said base and means adapted to center said support in the bore of a cylinder or the like having a valve-seat to be ground by said wheel, said support being vertically slidable with respect to said valve seat; a thimble upon said support in screw-threaded engagement therewith; an element of a scale upon said support. another element of said scale upon ,said thimble; means adapted to set said thimble againstrotation about said sup port while permitting rotation of said'support within said bore, and means adapted to limit the downward movement of the support to the extent indicated by the relation of the scale elements as predetermined by the settingof the thimble in accordancewith the depth of the, metal desired to be cutfit, with sliding contact the bore of the cylinder or the like whose valve-seat is to be ground, a micrometer upon said support in engagement therewith; means adapted to set said micrometer against rotation about said support while permitting rotation of said support within said bore, and'means adapted to limit the downward movement of the support consisting of a stop face upon said micrometer adapted to seat upon an element of the cylinders 5. In a machine for grinding valve-seats,

the combination ogf a motor, a cutting wheel driven thereby, a motor base, a support for said base vertically movableinthe valve guide bore, a thimble upon said support in screw-threaded engagement therewith; an element of a scale upon said support, another element of said scale upon said thimble; means adapted to set said thimble against rotation about said support while permitting rotation of said support within said bore, and means adapted to limit the downward movement of the support to the extent indicated by the relation of the scale elements 'as predetermined by the setting. of the thimble in accordance with the depth of the metal desired to be cut from said valve-seat. I

6. In a machinefor grinding valve-seats, the combination of a motor, a cutting wheel driven thereby, a motor base, a support for said base vertically movable in the valve guide bore, a micrometer upon said support in engagement therewith; means adapted to set said micrometer against rotation about said support while permitting rotation of said support within said bore, and means adapted to limit the downward movement.

of the support consisting of a stop face upon said micrometer adapted to seat upon an element of said valve guide. 7. In a machine for grinding valve seats, the combination of a motor, acutting wheel driven thereby, a motor base, a cylindrical stem extending downward from the base adapted to fit the valve guide bore and vertically movable therein, means for adjusting the height of the base relative to the valve seat comprising a ringhaving a screw threaded connection with the stem extending downward from the base and having its lower face adapted to receive support from the valve guide, andmeans adapted to set said ring against rotation of the stem within the valve guide bore.

In testimony whereof I afiix my signature.

- ALFRED J BERG. 

